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Axxxeman

One for the specialists: frequency split or filter

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Folks, I got a special problem. I am a guitarist (mostly rhythm guitar) and since several months our band cannot find a good bassist. I am considering the following idea:

  • signal path A should go by 4cm into the amp (standard guitar amp)
  • signal path B is used to produce a bass sound (octaver, compressor, bass amp simulation --> directly into FOH)

Problem is: I would want only the low notes of the guitar going into the bass signal path to not mudden the bass sound up. So I would need some filter that is letting through only the notes I play on the low E- and A-string in the range of little more than an octave. Meaning, every note that is played, that is higher than let's say f# should be filtered out. So I still could play chords, while signal path B would only process single line bass notes. That's about the idea.

 

My question is: Can that be realized with a Helix and if so ... HOW?

 

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IME experience with this, without a split pickup like a Roland or Variax, there really isn't a way to do this really cleanly like you're suggesting. Any harmonic information before your filter/split that reaches into the cutoff is going to be present, so even if you're technically fretting outside the range of your split/cutoff overtones/undertones may still be present and will be amplified by your "bass" rig. The only time this really works the way its intended for me (again, you may have better luck) is with single-note lines and just turning the bass rig signal chain off when I don't want any muddy/octave stuff. 

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13 minutes ago, Axxxeman said:

My question is: Can that be realized with a Helix and if so ... HOW?

 

 

Nope. To the best of my knowledge, no such device exists. You can't cherry pick specific notes to be routed to one path, but not the other. 

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Get a Variax and set the pitch of the E and A strings an octave down...

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Well, I am no expert, but I heard that it is possible to set an EQ in a way that a standard recording is turned into a karaoke version by just filtering out the voices' frequencies. If this is possible, filtering out deep notes should be possible, too, shouldn't it? I just have no idea how to set an EQ like this ...

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4 minutes ago, Axxxeman said:

Well, I am no expert, but I heard that it is possible to set an EQ in a way that a standard recording is turned into a karaoke version by just filtering out the voices' frequencies. If this is possible, filtering out deep notes should be possible, too, shouldn't it? I just have no idea how to set an EQ like this ...

There's usually a lot more going on than a simple EQ filter (phase filtering, dynamic frequency dependent compression) in those karaoke mixes, and if you've ever used an automated one that takes album recordings and makes them into karaoke versions, there is ALWAYS some leak from the lead vocal unless its a really old stereo recording with no spatial FX on the vocals. You could theoretically have a hard LP filter with an extreme slope set at 500Hz (or wherever you deem it necessary), but its going to require a very careful touch to get it so fill in bass frequnecies and not sound strange. I see quite a few two-piece bands with a guitarist simulating a bass/guitar rig, but they're usually doing a on/off thing and playing single note lines where they need the bass and guitar to match up, or just dealing with the muddiness that comes from playing chords into an octave pedal. A multi-output pickup is the ideal solution. 

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Well, a multi-output signal is no option at the moment. But I will try a low pass filter, combined with an EQ to see whether that can get me anywhere. Thanks!

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I know this is an older post, but a couple new pedals have come out since. Boss OC-5 or EHX Bass9. I’ve been trying to do this with my Helix, but am just biting the bullet and putting a Bass9 in the effects loop. 

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4 hours ago, jttaylor87 said:

I know this is an older post, but a couple new pedals have come out since. Boss OC-5 or EHX Bass9. I’ve been trying to do this with my Helix, but am just biting the bullet and putting a Bass9 in the effects loop. 

 

The Bass9 is a great tool... but you're still gonna have the same problem as the OP if the goal is to "manufacture" a bass line from whatever guitar part you're playing, and have it happen simultaneously. Even with a separate path just for the pedal, your still feeding it every note coming out of your guitar. There's no way to isolate notes from individual strings and route them to one path or the other.

 

But for adding bass lines to recordings if you don't own a bass, or if you just suck at playing one (like me) ... that pedal is awesome. ;)

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@cruisinon2- I feel you man! My understanding of the original post was that he wanted just the two low strings to be separately effected/octaved as bass notes. The Bass9 has a feature called "split bass" that does just that via polyphonic tracking, and splits the effected out to a separate jack from the dry guitar out. The OC-5 has a similar feature called "lowest range" that applies the octave/bass effect to only the lowest note in the chord being played, and also allows splitting of the dry (guitar) and effected (bass note) output. Either of them would require

 

To clarify - I plan to do this in the effects loop of my helix, but not because it requires a parallel path from the helix chain. It's rather so I can pull it in/out using a footswitch and set return 1 to the bass path and return 2 to the guitar signal chain. You could do the same thing in front of the unit, but would have to set the "returns" as the input to your parallel paths (at least on an LT, you could presumably use the aux in on the Helix Floor for the parallel chain).

 

Hopefully that helps!

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16 hours ago, jttaylor87 said:

@cruisinon2- I feel you man! My understanding of the original post was that he wanted just the two low strings to be separately effected/octaved as bass notes. The Bass9 has a feature called "split bass" that does just that via polyphonic tracking, and splits the effected out to a separate jack from the dry guitar out. The OC-5 has a similar feature called "lowest range" that applies the octave/bass effect to only the lowest note in the chord being played, and also allows splitting of the dry (guitar) and effected (bass note) output. Either of them would require

 

To clarify - I plan to do this in the effects loop of my helix, but not because it requires a parallel path from the helix chain. It's rather so I can pull it in/out using a footswitch and set return 1 to the bass path and return 2 to the guitar signal chain. You could do the same thing in front of the unit, but would have to set the "returns" as the input to your parallel paths (at least on an LT, you could presumably use the aux in on the Helix Floor for the parallel chain).

 

Hopefully that helps!

 

Fair enough... didn't know it was that sophisticated. I've used a buddy's once or twice, but didn't do a real deep dive into the features. Good to know...

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Again, I know I’m resurrecting an old thread, but it’s the most related. After diving into this with just the Helix, I was able to create a passable bass accompaniment to strummed /plucked guitar chords by using the frequency crossover split block. It takes the frequencies below a given hZ and sends them to one chain, while those above go to the other. Set around 200 hZ it does a pretty good job of sending fundamentals from the 5th feet of the D string (G3) to the “bass” signal path. You still get most of the regular guitar sound through the “guitar” path. Since it’s mostly the fundamental you’re getting on the bass side, it lacks some of the pop of normal wound strings, but with the guitar overtop it adds a great bass sound. I may upload the patch later for reference.

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